Apparatus for storing, handling and/or utilizing highly radioactive materials



March 31, 1964 R. BERNAS 3, 27,5 5

APPARATUS FOR STORING, HANDLING AND/0R UTILIZING HIGHLY RADIOACTIVEMATERIALS Filed Dec 23, 1959 Fig.1

42 RADIATION INDICATOR Fig 4 R m MNWM m m v m w. M O R United StatesPatent 3,127,515 AE PARATUS FOR STGRHNG, l-KANDLING AND/ GR UTEHZENGHIGHLY RADIOACTIVE MATERIALS Robert Bernas, 1 Rue Vidal-de-la-Blache,Paris 20, France Filed Dec. 23, 1959, Scr. No. 861,671 Claims priority,application France Dec. 3t), 1958 9 Claims. (Cl. 250106) This inventionrelates to improvements in apparatus of the type used in order tofacilitate the storage, handling and/or use of radioactive materials,including a body of substance that is highly absorbent of radiationenclosing within it a recess or cavity for receiving the radioactivesubstance (hereinafter sometimes referred to as the source) thereby toretain such substance in a protected position, means being provided formoving said substance between its said protected position and a positionof exposure, or use.

The invention is more especially, though not exclusively, applicable toapparatus of the above type wherein the radiation emitter or source, inmoving from its protected to its exposed position and vice versa, ispassed through a duct formed in the protective body or mass.

In any such apparatus the precise position at which the radioactivematerial is located at a given time is more or less uncertain. It hasbeen suggested in order to obviate this, in apparatus including a ductor channel through which the source is moved, to provide a series ofelectric contacts alongside the channel so that as the source support orcarrier moves past such contacts corresponding signal lamps are lighted,thereby indicating the position of the source. Such a device, however,will yield erroneous indications should the source material for anyreason become separated from its carrier; the operator may then be madeto believe mistakenly that the source has been restored to its protectedposition While it has actually remained in a more or less exposedposition in which it may be emitting dangerous radiation into surrounding space.

It is an object of the invention to provide means for positively andreliably indicating that the source is actually in its protectedposition. Another object is to provide means that will yield aneffective and usable indication should the source material become forany reason divided or separated. It is, consequently, a further objectto provide a device which will considerably reduce the hazards involvedin the handling and utilization of highly radioactive materials.

The apparatus according to the invention comprises, close to the pointat which the radioactive source material is located when in itsprescribed protected position, means responsive to radiations emitted bysaid source, the sensitivity or responsiveness of said means being sopredetermined that the means will not indicate the presence of radiationwhen the source is not located at its prescribed protected position butwill only yield such indication when the source is located exactly atsaid prescribed protected position or at a position sufiiciently closethereto as to ensure that effective protection is provided by theabsorbent material surrounding the source cavity.

It has already been proposed to use radiation-responsive means fordetecting the presence, absence, and/ or relative proximity of aradioactive substance. In this connection the prior art has madeavailable various types of detecting devices or cells having degrees ofsensitivity varying in increments over a wide range.

However, my present system in contradistinction to these prior detectingdevices employs such a disposition of the detecting means within theradiation-absorbing mass 3,127,515 Patented Mar. 31, 1964 that thesensitive detector or cell used therein can be subjected to radiationonly from the radioactive material emitted by the source within theapparatus, so that a positive reading given by the detector constitutesa reliable indication that the radioactive material actually is in itsprescribed protected position, and the absence of a positive readingshows that the substance is not in its prescribed protected position,either because it is in use or because of some accidental mishap orother occurrence.

The invention further includes an embodiment in which the sensitivity ofthe apparatus can be adjusted by interposing a filter made ofradiation-absorbing material, whereby the apparatus may be adapted foruse in various practical applications, including different ranges ofenergy rates of the radiations emitted by the radioactive materialsused.

In the ensuing description reference will be made by way of example tothe accompanying drawings, wherein:

FIG. 1 is a diagrammatic sectional view of one em bodiment;

FIG. 2 is a diagrammatic sectional view on a larger scale and taken nearthe detector cell;

FIG. 3 is similar to FIG. 2 and relates to a modified embodiment; and

FIG. 4 is a partial sectional view of another embodiment.

A radioactive material or source 10, such as an isotope, is containedwithin a carrier 11 forming part of a movable assembly which furtherincludes, on each side of the carrier, an elongated plug or rod,respectively designated 12 and 13, made of absorbing material. sembly isslidably received in a duct or channel 14 formed through a mass 15 ofabsorbent material, this duct being consequently straight and of uniformcross-section to enable the sliding displacement of rods 12, 13 therein.The apparatus further includes conventional means for passing theradioactive source material 10 from its prescribed protected position,shown in FIG. 1, where it is located in the center of the mass 15, to anexposed position exteriorly of said mass, and back to its protectedposition as desired.

In accordance with the invention a detector unit or cell 16 responsiveto radiation from the source material It) is positioned within the mass15 near the prescribed protected position of said source, and thesensitivity of the detector 16 is so selected or adjusted that thedetector cell will furnish a positive reading only when the source it)is actually in its prescribed protected position, or near enough to thatposition to ensure that the mass 15 will properly exert its protectivefunction.

Between the detector cell 16 and the position selected as the protectedposition for the source It a radiation filter or attenuator, such as ascreen of selected thickness made from a radiation-absorbent material,may be interposed.

The detector unit is desirably of the radio-resistive type, that is, itsresistance to electric current is varied with the rate of radiationstriking it. In such case the previously indicated condition can berestated as implying that the resistance of the detector cell mustremain constant so long as the radiation received by it from the sourcehas not attained a value corresponding to that received by it when thesource is in, or in immediate proximity to, its prescribed protectedposition, as explained above. Satisfactory results have been obtainedwhen using radiation-resistive cells comprising cadmium sulfite;gadolinium cells are also satisfactory. The dimensions should be smallenough to ensure that the cavity receiving the cell will notsubstantially impair the protective capacity of the absorbing mass orbody 15.

The detector cell is connected with the exterior circuit The asu byconductor means 17 leading to a terminal 18 on the outer surface of thebody 15.

Reference now will be made to FIG. 2. In this embodiment, the cavity 20receiving the radio-sensitive detector cell is defined between two cores21 and 22 of tungsten or other heavy metal, constituting the centralpart of the protective mass the remainder of which, shown at 23, is madeof lead. In the embodiment of FIG. 2, the cavity 20 is defined betweenthe inner front face 24 of core 22 and an inner end surface 25 formed inthe core 21.

In the modification of FIG. 3, the cavity 26 for the detector cell isformed between the outer surface 27 of one core 28 and the inner surface2% of the other core 30. In this construction an annulus 31 forming theinner end of the core 28 may be regarded as constituting a filterscreening the detector cell from the radiations from the sourcesupported by carrier 11.

In the modified construction of FIG. 4, the cell 16 is placed in arecess 32 defined at the end of a rod 33 made of lead or other heavymetal, and the opening of the recess 32 is sealed by a partitioningplate 34. The rod 33 is pushed into a channel or well 35 which is formedin the mass 36 of lead or the like and registers with another channel 37formed in the core 38, of tungsten or the like, constituting the centralcore of the protecting assembly. Removable means may if desired be usedfor attachment to the rod 33. In a modified construction, the core 38may be omitted, and the chimney 35 through the protecting mass may thenbe made to open directly into the channel 14. The channel 37 registerswith the recess 39 receiving the radioactive material 40 in protectedposition, and the plate 3 may be made from a material providing apartial screen for the cell 16 against radiation emitted by source 40.The detector cell 16 could also be incorporated in the sealing plate 34.A conductor 41 extending along a sinuous path is imbedded in the rod 33and is connected with a terminal 113 at the end of the rod forconnecting detector 16 with an electric measuring circuit 42 forindicating the variations in resistance of the detector cell when thelatter is exposed to the radiation from the source.

The rod 33 is shown carried by a base 43 which incorporates themeasuring circuit d2 serving to indicate the variations in resistance.

What I claim is:

1. An apparatus for the storing and handling of a radiation emitter,comprising a protective mass adapted to shield the operating personnelfrom said radiation upon the lodging of said emitter substantially atthe center of said mass, said mass being provided with a straight ductof uniform cross-section open at its ends and passing substantiallythrough said center, a carrier for said emitter movably disposed in saidduct, a pair of elongated plugs slidably fitting within said duct onopposite sides of said carrier, said plugs being composed of a materialadapted to absorb radiation from said source, thereby substantiallyblocking the passage of radiation from said source through said duct ina position of said source within said mass, said carrier and said plugsbeing displaceable within said duct between a shielded position nearsaid center and an exposed position remote therefrom in which saidcarrier lies outside said mass, a radiation-sensitive cell positionedwithin said mass in the vicinity of said shielded position adjacent thepath of displacement of said carrier, and electrical circuit meansconnected to said cell for providing externally of said mass anindication of the intensity of irradiation of said cell by said emitter.

2. In an apparatus for the storing and handling of a radiation emitter,in combination, a body of protetcive material adapted to shield saidemitter upon the withdrawal of the latter during periods of non-use intoa shielded position substantially at the center of said body, said bodybeing provided with a straight duct of uniform cross-section open at itsends and passing substantially through said center, a carrier for saidemitter movably disposed in said duct, a pair of elongated plugsslidably fitting within said duct on opposite sides of said carrier,said plugs being composed of a material adapted to absorb radiation fromsaid source, thereby substantially blocking the passage of radiationfrom said source through said duct in the shielded position of saidsource, said body being provided With a channel extending substantiallytransversely to said duct and opening into same at said shieldedposition, a rod of heavy metal tightly fitting into said channel andsubstantially filling same while having an outer end substantially levelwith the exterior of said body, said body being provided at its oppositeend with a recess facing said duct, a cell sensitive to the radiation ofsaid source in said recess, electric connector means extending from saidcell to the exterior of said body, and indicator means coupled to saidconnector means externally of said body for signaling the intensity ofradiation impinging upon said cell.

3. The combination according to claim 2 wherein said rod is provided atits outer end with a base rigidly attached thereto, said indicator meansbeing mounted on said base.

4. An apparatus for storing and handling a radioactive source,comprising a carrier for said source; a mass for protecting surroundingpremises from radiation emitted by the source when not in use; said massbeing provided with an elongated straight duct of uniform crosssectionopen at its ends for permitting movement of said carrier and said sourcefrom a protected position wherein said source is disposed within saidmass to an exposed position wherein said source is disposed exteriorlyof said mass and vice versa; a pair of elongated plugs slidably fittingwithin said duct on opposite sides of said carrier, said plugs beingcomposed of a material adapted to absorb radiation from said source,thereby substantially blocking the passage of radiation from said sourcethrough said duct in the protected position of said source, said massfurther having a recess located adjacent said duct at said protectedposition; an element sensitive to the radiation of said source in saidrecess; and indicating means connected to said element for providingexternally of the mass a first indication when the source is at saidprotected position and another indication when the source is not at saidprotected position.

5. An apparatus for storing and handling a radioactive source comprisinga carrier for said source; a protective mass provided with a straightduct of uniform cross-section open at its ends for permitting movementof said carrier and said source; a pair of elongated plugs slidablyfitting within said duct on opposite sides of said carrier, said plugsbeing composed of a material adapted to absorb radiation from saidsource, thereby substantially blocking the passage of radiation fromsaid source through said duct in a position of said source within saidmass; a first heavy-metal core portion and a second heavy-metal coreportion jointly constituting a core for said protective mass traversedby said duct, said portions defining between each other a recesscommunicating with said duct; an element sensitive to the radiation ofsaid source in said recess; and indicating means located externally ofsaid mass and connected with said element to provide differentindications varying with the distance of said source substantially atthe center of said core.

6. An apparatus for storing and handling a radioactive source,comprising a carrier for said source; a protective mass provided with astraight duct of uniform crosssection open at its ends for permittingmovement of said carrier and said source through the mass; a pair ofelongated plugs slidably fitting within said duct on opposite sides ofsaid carrier, said plugs being composed of a material adapted to absorbradiation from said source, thereby substantially blocking the passageof radiation from said source through said duct in a position of saidsource Within said mass; a first heavy-metal core portion and a secondheavy-metal core portion jointly constituting a core for said protectivemass traversed by said duct, said portions defining between each other arecess separated from said duct by a part of said core and locatedadjacent to a prescribed source-storage position substantially at thecenter of said core, an element sensitive to the radiation from saidsource disposed in said recess; and indicating means located externallyof said mass and connected with said element to provide differentindications varying with the distance of said source from saidsource-storage position.

7. An apparatus for storing and handling a radioactive source,comprising a carrier for said source; a protective mass provided with astraight duct of uniform cross-section open at its ends for permittingmovement of said source between a protected position locatedsubstantially at the center of said mass and an exposed positionexteriorly thereof; a pair of elongated plugs slidably fitting withinsaid duct on opposite sides of said carrier, said plugs being composedof a material adapted to absorb radiation from said source, therebysubstantially blocking the passage of radiation from said source throughsaid duct in the protected position of said source; a slidable memberextending through said mass between the exterior thereof and said duct,said member being provided with a recess at one end thereof adjacentsaid duct; a plate of heavy-atomic material sealing the opening of saidrecess adjacent said duct; an element sensitive to the radiation of saidsource in said recess; conductor means imbedded in said member andconnected to said element; and indicating means connected to saidconductor means and controlled by said element.

8. An apparatus for the storing and handling of a radiation emitter,comprising a protective mass adapted to shield the operating personnelfrom said radiation upon the lodging of said emitter substantially atthe center of said mass, said mass being provided with a straight ductof uniform cross-section provided with an open end passing substantiallythrough said center, a carrier for said emitter movably disposed in saidduct, an elongated plug slidably fitting within said duct between saidcarrier and said open end, said plug being composed of a materialadapted to absorb radiation from said source, thereby substantiallyblocking the passage of radiation from said source through said duct ina position of said source within said mass, said carrier and said plugsbeing displaceable within said duct between a shielded position in whichsaid carrier lies near said center and an exposed position remotetherefrom in which said carrier lies outside said mass, aradiation-sensitive cell positioned within said mass in the vicinity ofsaid shielded position adjacent the path of displacement of saidcarrier, and electrical circuit means connected to said cell forproviding externally of said mass an indication of the intensity ofirradiation of said cell by said emitter.

9. An apparatus for storing and handling a radioactive source,comprising a carrier for said source; a mass for protecting surroundingpremises from radiation emitted by the source when not in use; said massbeing provided with a straight duct of uniform cross-section providedwith an open end for permitting movement of said carrier and said sourcefrom a protected position wherein said source is disposed Within saidmass to an exposed position wherein said source is disposed exteriorlyof said mass and vice versa; an elongated plug slidably fitting withinsaid duct between said carrier and said open end, said plug beingcomposed of a material adapted to absorb radiation from said source,thereby substantially blocking the passage of radiation from said sourcethrough said duct in the protected position of said source, said massfurther having a recess located adjacent said duct at said protectedposition; an element sensitive to the radiation of said source in saidrecess; and indicating means connected to said element for providingexternally of the mass a first indication when the source is at saidprotected position and another indication when the source is not at saidprotected position.

References Cited in the file of this patent UNITED STATES PATENTS Re.24,544 Morganstern Sept. 30, 1958 2,315,819 Schlesman Apr. 6, 19432,456,233 Wolf Dec. 14, 1948 2,594,970 Monk Apr. 29, 1952 2,597,535Serge May 20, 1952 2,640,936 Pajes June 2, 1953 2,843,753 Meeder July15, 1958 2,916,628 Prest Dec, 8, 1959 2,937,275 Thourson et al. May 17,1960 2,971,089 Haywood Feb. 7, 1961 2,998,519 Tunnicliife et a1. Aug.29, 1961 2,998,522 Martin et a1. Aug. 29, 1961 FOREIGN PATENTS 793,905Great Britain Apr. 23, 1958

1. AN APPARATUS FOR THE STORING AND HANDLING OF RADIATION EMITTER,COMPRISING A PROTECTIVE MASS ADAPTED TO SHIELD THE OPERATING PERSONNELFROM SAID RADIATION UPON THE LODGING OF SAID EMITTER SUBSTANTIALLY ATTHE CENTER OF SAID MASS, SAID MASS BEING PROVIDED WITH A STRAIGHT DUCTOF UNIFORM CROSS-SECTION OPEN AT ITS ENDS AND PASSING SUBSTANTIALLYTHROUGH SAID CENTER, A CARRIER FOR SAID EMITTER MOVABLY DISPOSED IN SAIDDUCT, A PAIR OF ELONGATED PLUGS SLIDABLY FITTING WITHIN SAID DUCT ONOPPOSITE SIDES OF SAID CARRIER, SAID PLUGS BEING COMPOSED OF A MATERIALADAPTED TO ABSORB RADIATION FROM SAID SOURCE, THEREBY SUBSTANTIALLYBLOCKING THE PASSAGE OF RADIATION FROM SAID SOURCE THROUGH SAID DUCT INA POSITION OF SAID SOURCE WITHIN SAID MASS, SAID CARRIER AND SAID PLUGSBEING DISPLACEABLE WITHIN SAID DUCT BETWEEN A SHIELDED POSITION NEARSAID CENTER AND AN EXPOSED POSITION REMOTE THEREFOM IN WHICH SAIDCARRIER LIES OUTSIDE SAID MASS, A RADIATION-SENSITIVE CELL POSITIONEDWITHIN SAID MASS IN THE VICINITY OF SAID SHIELDED POSITION ADJACENT THEPATH OF DISPLACEMENT OF SAID CARRIER, AND ELECTRICAL CIRCUIT MEANSCONNECTED TO SAID CELL FOR PROVIDING EXTERNALLY OF SAID MASS ANINDICATION OF THE INTENSITY OF IRRADIATION OF SAID CELL BY SAID EMITTER.